@misc{W1516111018,
  author = {Michael I. Jordan and Zoubin Ghahramani and Tommi Jaakkola and Lawrence K. Saul},
  title = {An Introduction to Variational Methods for Graphical Models},
  year = {1999},
  howpublished = {Machine Learning},
  doi = {https://doi.org/10.1023/a:1007665907178}
}